1. Field of the Invention
The present invention relates to an endoscope apparatus that observes an inside of a subject using an endoscope.
2. Description of the Related Art
Generally, an endoscope apparatus includes an endoscope that has an image pickup device for photographing in vivo tissue as an object and a light guide that transmits an illuminating light for illuminating the object, a processor as a signal processing apparatus that processes a video signal from the image pickup device inside the endoscope and outputs a processed signal to a monitor, and a light source apparatus that supplies an illuminating light to the light guide inside the endoscope.
In endoscope apparatuses of this kind, in some cases a common light source apparatus is utilized even when endoscopes of different kinds are used, such as, for example, an upper digestive tract endoscope and a lower digestive tract endoscope. Even when using endoscopes of different kinds, it is desirable that an observed image that has good color reproducibility can be displayed on a monitor.
An endoscope apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 8-126607 as a first conventional example includes luminous flux control means that controls the luminous flux of light-source light that is supplied to a light guide, by means of an applied voltage of a light source lamp and a diaphragm that blocks an optical path.
According to the first conventional example, in accordance with the control state of the luminous flux of light-source light, with respect to an image signal of an endoscopic image obtained by an image pickup device, color tone correction means performs color tone correction separately for each portion of the endoscopic image that is divided into a plurality of portions (plurality of regions).
When picking up a color image under white color illuminating light that spans the visible wavelength band, for the visible wavelength band also, the numerical apertures of light guides for different wavelengths in the wavelength band have respectively different values.
Accordingly, with respect to the visible wavelength band also, if color correction is not performed in accordance with the respective numerical apertures for a plurality of respectively different wavelengths in the wavelength band, it is difficult to obtain an endoscopic image as an observation image with good color reproducibility.
In this connection, in a light source apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2006-26128 as a second conventional example, a connector section is formed to which a light guide is connected, in which a visible light source that generates visible light and an excitation light source that generates excitation light are provided, and in which optical paths of the visible light and excitation light from the two light sources are made common by an optical path synthesizing element.
The second conventional example discloses a configuration in which a luminous flux diameter produced by a condensing lens that condenses visible light is switched in accordance with a numerical aperture of a light guide of an endoscope connected to the connector section of the light source apparatus. That is, the second conventional example only discloses switching of a luminous flux diameter produced by a condensing lens that condenses light, in accordance with a numerical aperture of a light guide of an endoscope. Although conventionally, with respect to the design of endoscope apparatuses, a light guide has been selected that has an NA that conforms to a specification for the light condensing characteristics of the light source apparatus, in recent years the situation is such that light guides of various characteristics that are different from those assumed at the time of designing the endoscope apparatus are used for endoscope apparatuses that include identical light source apparatuses.